Gravel Spit-Inlet Dynamics: Orford Spit, UK

Abstract

The Orford Spit and Ness complex on the gravel-dominated shoreline of Suffolk, eastern England comprises over 350 ha of beach ridge shoreline that diverts the channel of the Alde estuary c. 12 km southward. Centuries of progradation have formed an extensive foreland at Orford Ness, but south of this, Orford Spit has exhibited significant phases of growth and retreat which are in part linked to the dynamics of Orford Haven, the inlet and ebb-delta system at the mouth of the Alde/Ore estuary. Examination of an extended history (500 years) of this system shows a definitive reduction in scales of change over the centuries, and implies a decrease in sediment availability and transport, and a shift from sediment sink to sediment source. Spit dynamics are instrumental in the development and decay of transient lagoons and estuary-oriented spits which rely on breaching, ebb delta bypassing and changes in protection facilitated by the shifting spit.